Plate heat exchanger and reversible refrigerating machine including such an exchanger

ABSTRACT

This exchanger ( 1100 ), including superposed plates ( 2 A- 2 L) which are inserted between two end plates ( 11, 12 ) and which define channels for circulation of heat-exchanging fluid. These channels delimit a first circuit (C 1 ) for circulation of a first heat-exchanging fluid, comprising a single pass, and a second circuit (C 2 ) for circulation of a second heat-exchanging fluid, comprising two passes opposite one another, so that, for each direction of circulation of the second heat-exchanging fluid in the second circuit, one of the two passes of the second circuit is co-current with respect to the pass of the first circuit, while the other of the two passes of the second circuit is counter-current with respect to the pass of the first circuit.

The present invention relates to a plate heat exchanger as well as to a refrigerating machine including such an exchanger.

FIG. 1 shows a brazed plate heat exchanger 100, provided with a set of superposed plates 2A, 2B and 2C. Each plate 2A, 2B and 2C has its opposite surfaces corrugated according to a precise scheme, for example, a chevron profile. The edges of the plates are provided with gaskets to prevent fluid leaks. The plates 2A, 2B and 2C are arranged against one another, between two end plates 11 and 12, so that the corrugated surfaces of two adjacent plates together define channels 20 for the circulation of heat-exchanging fluids.

Each plate 2A, 2B and 2C and each end plate 11 and 12 comprises four openings each produced in one of their corners, namely a first opening 21 which is used as inlet E1 for a first heat-exchanging fluid, a second opening 22 which is used as outlet S1 for the first heat-exchanging fluid, a third opening 23 which is used as inlet E2 for a second heat-exchanging fluid, and a fourth opening 24 which is used as outlet S2 for the second heat-exchanging fluid. The channels 20 defined against each corrugated surface receive the first or the second heat-exchanging fluid. In the example of FIG. 1, the first heat-exchanging fluid circulates in a first circuit between the second and third plates 2B and 2C. The second heat-exchanging fluid circulates in a second circuit which extends between the plates 2A and 2B. Thus, the first and second heat-exchanging fluids circulate alternately between two adjacent plates 2A, 2B and 2C so as to ensure a transfer of thermal energy between the fluids.

FIG. 2 shows a reversible refrigerating machine which includes a compressor 400, a pressure reducing valve 200 and two exchangers 100 and 300 similar to the exchanger of FIG. 1. These four elements are mounted on a common circuit C of refrigerant fluid. The exchangers 100 and 300 work alternately as condenser or evaporator depending on whether the refrigerating machine operates in heating mode or in air conditioning mode, the change in mode occurring by changing the direction of circulation of the refrigerant fluid in the common circuit C.

The first exchanger 100 implements a heat transfer between the common circuit C and a first exchange circuit C10. The second exchanger 300 implements a heat transfer between the common circuit C and a second exchange circuit C20.

For each operating mode, for example, one of the exchangers 100 and 300 runs counter-currently with respect to the exchange circuit C10 or C20 which interacts with this exchanger, while the other exchanger runs co-currently with respect to the other exchange circuit C10 or C20.

The performances of a plate heat exchanger are better counter-currently than co-currently, so that for each operating mode, one of the exchangers 100 and 300 does not have an optimized yield.

DE 10 2006 002 018 discloses a reversible refrigerating machine which makes it possible to change the operating mode without reversing the direction of circulation of the refrigerant fluid, using a three-way valve installed on the refrigerating circuit. This solution is complex to implement, since it requires the installation of a device for distributing the refrigerant fluid.

These are the disadvantages that the invention aims to remedy more particularly by proposing a novel plate exchanger which is easy to use in a reversible refrigerating machine and which has a satisfactory yield.

To this effect, the invention relates to a plate heat exchanger including superposed plates which are inserted between two end plates and which define channels for circulation of heat-exchanging fluid, characterized in that the channels delimit

-   -   a first circuit for circulation of a first heat-exchanging         fluid, comprising a single pass, and     -   a second circuit for circulation of a second heat-exchanging         fluid, comprising two passes opposite from one another,     -   so that, for each direction of circulation of the second         heat-exchanging fluid in the second circuit, one of the two         passes of the second circuit is co-current with respect to the         pass of the first circuit, while the other of the two passes of         the second circuit is counter-current with respect to the pass         of the first circuit.

According to advantageous but non-obligatory aspects of the invention, such an exchanger can incorporate one or more of the following features, considered in any technically acceptable combination:

-   -   the first circuit comprises several intermediate branches each         delimited between two adjacent plates and connecting to one         another in parallel a forward branch and a return branch of the         first circuit;     -   the second circuit comprises two adjacent zones, in which         intermediate branches of the second circuit belong, for one of         these zones, to one of the two passes of the second circuit, and         for the other zone, to the other of the two passes of the second         circuit;     -   the second circuit comprises a first portion and a second         portion, which are separated by an intermediate plate of the         exchanger and which are connected to one another by a conduit         outside of the exchanger;     -   the exchanger includes a tube which is provided with a slot         distributing the second heat-exchanging fluid in several         channels of the second circuit.

Another aspect of the invention relates to a reversible refrigerating machine including a common circuit of refrigerating fluid, on which are arranged a compressor, a pressure reducing valve and two exchangers which are each as defined above.

According to advantageous but non-obligatory aspects of the invention, such a refrigerating machine can incorporate one or more of the following features, considered in any technically acceptable combination:

-   -   the refrigerating machine comprises a four-way valve capable of         changing the direction of circulation of the refrigerant fluid         in the common circuit;     -   the common circuit is formed by the second circuit of the         exchangers;     -   the second circuit comprises an inlet and an outlet arranged at         the top of the exchangers;     -   the second circuit comprises an inlet and an outlet arranged at         the bottom of the exchangers.

The invention will be understood better, and other advantages of said invention will become clearer in light of the following description of a plate exchanger according to the invention, which is given only as an example and in reference to the drawings in which:

FIG. 1 is an exploded perspective view of a plate exchanger of the prior art;

FIG. 2 is a diagrammatic view of a reversible refrigerating machine of the prior art;

FIG. 3 is an exploded diagrammatic view of an exchanger according to a first embodiment of the invention;

FIGS. 4 and 5 are diagrams of the exchanger of FIG. 3 with a first and a second direction of circulation, respectively, of the heat-exchanging fluids;

FIGS. 6 and 7 are diagrams of refrigerating machines including the exchanger of FIG. 3;

FIG. 8 is a diagram of the exchanger of FIG. 3 according to another orientation;

FIG. 9 is an exploded perspective view of an exchanger according to a second embodiment of the invention;

FIGS. 10 and 11 are diagrams of the exchanger of FIG. 9 with a first and a second direction of circulation, respectively, of the heat-exchanging fluids;

FIGS. 12 and 13 are diagrams of a tube for distributing fluid;

FIGS. 14 to 17 are diagrams of an exchanger according to a third embodiment of the invention, with different directions of circulation of the heat-exchanging fluids;

FIGS. 18 to 21 are diagrams of an exchanger according to a fourth embodiment of the invention, with different directions of circulation of the heat-exchanging fluids; and

FIGS. 22 and 23 are diagrams of the tube of FIGS. 12 and 13, positioned for an exchanger in one of the configurations of FIGS. 14, 15, 18 and 19 and for one of the configurations of FIGS. 16, 17, 20 and 21, respectively.

FIG. 3 shows a plate exchanger 1100 according to the invention. It includes a first end plate 11 which defines a first external surface A of the exchanger 1100, and a second end plate 12 which defines a second external surface B of the exchanger 1100 opposite the first surface A.

Twelve plates 2A to 2L are superposed, that is to say arranged successively, one against the other, between the end plates 11 and 12. The plate 2K is arranged against the first end plate 11, and the plate 2L is arranged against the second end plate 12.

The end plates 11 and 12 and the plates 2A to 2L have an overall rectangular shape. The exchanger 1100 has an overall parallelepiped shape with rectangular base. M is used to designate an upper edge of the exchanger 1100 located at the top of FIG. 3, and N is used to designate a lower edge of the exchanger 1100 parallel to the upper edge M and located at the bottom of FIG. 3. The edges M and N are of small length and connect together long edges O and P of the end plates 11 and 12 and of the plates 2A to 2L, which are perpendicular to the short edges M and N. The long edge O is located in the foreground of FIG. 3 and the long edge P in the background.

Each plate 2A to 2L comprises two opposite rectangular surfaces which are corrugated according to a precise scheme which does not limit the invention, for example, a chevron profile. These corrugations are not represented in FIG. 3; they can be similar to those of the exchanger of FIG. 1. The edges M, N, 0 and P of the plates 2A to 2L are provided with brazed gaskets, not shown, in order to prevent fluid leaks. The corrugated surfaces facing one another of two adjacent plates 2A to 2L together define channels for the turbulent circulation of heat-exchanging fluids, these channels not being shown in FIG. 3 but possibly similar to the channels 20 of FIG. 1.

In the direction of its thickness, the exchanger 1100 comprises a first zone Z1, between the first end plate 11 and the plate 2E, and a second zone Z2, between the plate 2F and the second end plate 12. The zones Z1 and Z2 are adjoining. The first zone Z1 is located on the side of the first surface A of the exchanger 1100, and the second zone Z2 is located on the side of the second surface B. The zones Z1 and Z2 divide the exchanger 1100 in two in its thickness, that is to say in a direction perpendicular to the end plates 11 and 12 and to the plates 2A to 2L.

The exchanger 1100 delimits two heat-exchanging fluid circuits C1 and C2. For use in a refrigerating machine, the first circuit C1 is provided for water and the second circuit C2 for a refrigerant fluid. The first circuit C1 corresponds to one of the exchange circuits C10 or C20 of the refrigerating machine of FIG. 2, and the second circuit C2 corresponds to the common circuit C.

The circuits C1 and C2 are defined so that the water circuit C1 comprises a single pass, that is to say the fluid circulates between the edges N and M in a single direction, namely from bottom to top in the example of FIG. 3. The refrigerant fluid circuit C2 comprises two passes, namely an inlet pass in the zone Z2, where the refrigerant fluid circulates in a first direction, namely from bottom to top between the edges N and M, and an outlet pass in the zone Z1, where the refrigerant fluid circulates in a second direction opposite from the first direction, that is to say from top to bottom between the edges M and N.

This configuration results from the particular arrangement of the corrugations of the plates 2A to 2L and of the holes 21 to 24 produced in the corners of the end plates 11 and 12 and of the plates 2A to 2L as described below. The end plates 11 and 12 and the plates 2A to 2L are each provided with a number of holes between one and four, so as to guide the circulation of the fluids in the circuits C1 and C2.

The hole 21 is located in a first lower corner, at the junction between the edges N and P. The hole 22 is located in a second lower corner, at the junction between the edges N and O. The hole 23 is located in a first upper corner, at the junction between the edges M and P. The hole 24 is located in a second upper corner, at the junction between the edges M and O.

For a first direction of circulation of the fluids in the circuits C1 and C2, as defined in FIG. 3, an inlet E1 of the first circuit C1 is formed by a first hole 21 of the second end plate 12, in the zone Z2. The first circuit C1 comprises a first lower branch or forward branch C11 in which the fluid circulates up to the plate 2K, through holes 21 which are perforated in each plate 2A to 2J and 2L. The first end plate 11 and the plate 2K have no hole 21. A second upper branch or return branch C12 of the first circuit C1 is defined between the plate 2K and a hole 23 of the second end plate 12, which defines an outlet S1 of the first circuit C1 in the second zone Z2. The first end plate 11 and the plate 2K have no hole 23. Between the plates 2K and 2L, the fluid circulates through holes 23 perforated in each plate 2A to 2J and 2L.

Between the branches C11 and C12, the first circuit C1 comprises several intermediate branches C13 to C18 connected in parallel between the branches C11 and C12. The intermediate branches C13 to C18 are represented in a rectilinear manner in the diagram of FIG. 3, but in practice they meander in the pattern defined by the corrugations of the plates 2A to 2L.

The branches C13 to C15 are part of the second zone Z2, and the branches C16 to C18 are part of the first zone Z1.

Thus, in the zones Z1 and Z2, the first circuit C1 has a single pass from the edge N and towards the edge M. In other words, between the edges N and M and for the two zones Z1 and Z2, the fluid circulates in the first circuit C1 in a single direction, namely from bottom to top.

The remainder of the description concerns the second circuit C2. An inlet E2 of the second circuit C2 is formed by a hole 22 of the second end plate 12, in the second zone Z2. The second circuit C2 comprises a first lower branch C21, which extends exclusively in the second zone Z2 and which connects the second inlet E2 to a first and a second intermediate branch C22 and C23 connected in parallel between the lower branch C21 and an upper branch C24. In the intermediate branches C22 and C23, the fluid circulates from bottom to top, from the edge N to the edge M. The plates 2F and 2G have no hole 22.

The upper branch C24 extends through holes 24 perforated in the plates 2B to 21 in zones Z1 and Z2, and it is connected to two other intermediate branches C25 and C26 in which the fluid circulates from top to bottom, from the edge M to the edge N. The intermediate branches C25 and C26 connect in parallel the upper branch C24 to a second lower branch C27, which extends exclusively in the first zone Z1, through holes 22 perforated in the plates 2A to 2C, 2K and in the first end plate 11, up to an outlet S2 of the second circuit C2 formed by the hole 22 of the end plate 11, in the first zone Z1.

Thus, in the zone Z2, the second circuit C2 has an inlet pass where the fluid circulates in a first direction, namely from the lower edge N and towards the upper edge M. In the zone Z1, the second circuit C2 has an outlet pass where the fluid circulates in a second direction opposite from the first direction, namely from the upper edge M and towards the lower edge N.

FIGS. 4 and 5 more diagrammatically again show the arrangement of the circuits C1 and C2 of the exchanger 1100. FIG. 4 corresponds to the first direction of circulation of FIG. 3 for the circuit C2, and FIG. 5 to a second opposite direction of circulation.

The first direction of circulation of FIGS. 3 and 4 corresponds to a first operating mode, in which the exchanger 1100 operates by evaporation. In the second zone Z2, the refrigerant fluid of the circuit C2 performs a first pass that is co-current with respect to the water of the circuit C1, it circulates from bottom to top between the edges N and M and, in the first zone Z1, the refrigerant fluid of the circuit C2 performs a second pass that is counter-current with respect to the water of the circuit C1, it circulates from top to bottom between the edges M and N.

In FIG. 5, the direction of circulation of the refrigerant fluid in the second circuit C2 is reversed. The direction of circulation of the water in the circuit C1 remains unchanged. The inlet E2 of the circuit C2 becomes the outlet S2 and vice versa. The exchanger 1100 then operates in a second mode, by condensation.

In this second mode, for the first zone Z1, the refrigerant fluid in the second circuit C2 performs a first pass that is co-current with respect to the water of the first circuit C1, it circulates from bottom to top from the lower edge N towards the upper edge M, and, in the second zone Z2, the refrigerant fluid in the second circuit C2 performs a second pass that is counter-current with respect to the water of the first circuit C1, it circulates from top to bottom from the upper edge M towards the lower edge N.

Thus, for each operating mode, the exchanger 1100 makes it possible for the refrigerant fluid of the circuit C2 to perform a first pass that is co-current and a second pass that is counter-current with respect to the water of the circuit C1. In this manner, the thermal yield of the exchanger 1100 is improved, since, in each operating mode, the fluids of the circuits C1 and C2 circulate counter-currently for the zone corresponding to the outlet pass of the circuit C2.

FIGS. 6 and 7 show a reversible refrigerating machine which includes a compressor 400, a pressure reducing valve 200, and two exchangers 1100 and 1200 each similar to the exchanger of FIGS. 3 to 5. These four elements 400, 200, 1100 and 1200 are mounted on a common circuit C of refrigerant fluid.

The first exchanger 1100 implements a heat transfer between the common circuit C and a first exchange circuit C10. The second exchanger 1200 implements a heat transfer between the common circuit C and a second exchange circuit C20.

The exchangers 1100 and 1200 operate alternately as condenser or evaporator depending on whether the refrigerating machine operates in heating mode or in air conditioning mode. The change in mode occurs by changing the direction of circulation of the refrigerant fluid in the common circuit C using a four-way valve V1.

In FIG. 6, for the first operating mode, the exchanger 1100 operates by condensation, and the second exchanger it operates by evaporation. The valve V1 is in a first position. The refrigerant fluid of the common circuit C circulates in a first direction. The first exchange circuit C10 is a hot water circuit, and the second exchange circuit C20 is a cold water circuit.

In FIG. 7, for the second operating mode, the exchanger 1100 operates by evaporation, and the second exchanger operates by condensation. The valve V1 is in a second position. The refrigerant fluid of the common circuit C circulates in a second direction opposite from the first direction of FIG. 6. The first exchange circuit C10 is a cold water circuit, and the second exchange circuit C20 is a hot water circuit.

For each operating mode, each of the exchangers 1100 and 1200 operates, for one of the zones Z1 and Z2, counter-currently, while for the other zone Z2 or Z1, the exchangers 1100 and 1200 operate co-currently.

More precisely, in the first operating mode represented in FIG. 6, and for each exchanger 1100 and 1200, the first pass or inlet pass of the common circuit C in the zone Z2 is performed co-currently with respect to the corresponding exchange circuit C10 or C20, and the second pass or outlet pass of the common circuit C in the zone Z1 is carried out counter-currently with respect to the corresponding exchange circuit C10 or C20. This configuration corresponds to that of FIG. 4.

In the second operating mode represented in FIG. 7 and for each exchanger 1100 and 1200, the first pass or inlet pass of the common circuit C in the zone Z1 is performed co-currently with respect to the corresponding exchange circuit C10 or C20, and the second pass or outlet pass of the common circuit C in the zone Z2 is carried out counter-currently with respect to the corresponding exchange circuit C10 or C20. This configuration corresponds to that of FIG. 5.

In FIGS. 3 to 7, the exchanger 1100 is arranged according to a first orientation, in which the inlets E1 and E2 of the circuits C1 and C2 are arranged at the bottom of the exchanger 1100, along the lower edge N. The fluid of the circuit C1, in the two zones Z1 and Z2, and the fluid of the circuit C2, in the zone Z2 for the configuration of FIG. 4, and in the zone Z1 for the configuration of FIG. 5, circulate upwards, against the force exerted by gravity.

FIG. 8 shows the exchanger 1100 according to a second orientation, in which the edge M is oriented towards the bottom, while the edge N is oriented towards the top. The inlets E1 and E2 of the circuits C1 and C2 are arranged at the top of the exchanger 1100, along the upper edge M. The fluid of the circuit C1, in the two zones Z1 and Z2, and the fluid of the circuit C2, in the zone Z1, circulate downward in the direction of the force exerted by gravity.

For the two orientations of the exchanger 1100, the flow of the water in the circuit C1 is counter-current with respect to the flow of the refrigerant fluid in the outlet pass of the circuit C2, that is to say the flow of the water is directed upward when the inlet E2 and the outlet S2 are at the bottom, as shown in FIGS. 4 to 7, and is directed downward when the inlet E2 and the outlet S2 are at the top, as shown in FIG. 8.

FIG. 9 shows an exchanger 2100 according to a second embodiment of the invention, of the dual-circuit exchanger type. The elements of the exchanger 2100 similar to those of the exchanger 1100 bear the same reference numbers. Below, the elements of the exchanger 2100 that are similar to those of the exchanger 1100 are not described in detail.

As described below and in contrast to the exchanger 1100, the exchanger 2100 comprises two independent refrigerant fluid circuits C2 and C′2, which can implement two passes when they are connected to one another appropriately by means of a duct C3 represented with dotted lines in FIG. 9. The duct C3 is represented diagrammatically in FIGS. 10 and 11 which are described in greater detail below.

The exchanger 2100 comprises two end plates 11 and 12 and eight corrugated plates 2A to 2H arranged between the end plates 11 and 12. The exchanger 2100 also has an intermediate end plate 13 inserted between the plates 2D and 2E. The intermediate end plate 13 materially delimits the separation between the zones Z1 and Z2.

The exchanger 2100 has a generally rectangular shape and comprises an upper edge M, a lower edge N, and two lateral edges O and P. The end plates 11, 12 and 13 and the plates 2A to 2H are provided with holes 21, 22, 23 and/or 24.

The first circuit C1 provided, for example, for water in the case in which a refrigerating machine is used, comprises an inlet E1 implemented by a hole 24 produced in the end plate 11. The first circuit C1 comprises a first branch or forward branch C11 which starts from the inlet E1 and passes through holes 24 produced in the plates 2A to 2G as well as in the intermediate end plate 13. A second lower branch or return branch C12 of the first circuit starts at the outlet S1 and passes through holes 22 produced in the plates 2A to 2G as well as in the intermediate end plate 13. Between the end plate 11 and the plate 2H, the fluid circulates through holes 22 perforated in each plate 2A to 2G.

Between the branches C11 and C12, the first circuit C1 comprises several intermediate branches C13 to C16 connected in parallel between the branches C11 and C12. The intermediate branches C13 to C16 are represented in a rectilinear manner in the diagram of FIG. 9, but in practice they meander in the pattern defined by the corrugations of the plates 2A to 2H.

The branches C13 and C14 are part of the first zone Z1, and the branches C15 and C16 are part of the second zone Z2.

Thus, in the zones Z1 and Z2, the first circuit C1 has a single pass, from the upper edge M and towards the lower edge N. In other words, between the edges M and N and for the two zones Z1 and Z2, the fluid circulates in the first circuit C1 in a single direction, namely from top to bottom.

The remainder of the description concerns the circuits C2 and C′2 of refrigerant fluid.

The circuit C2 comprises an inlet E20 formed by a hole 23 produced in the end plate 12. A first upper branch C21 or forward branch of the circuit C2 extends from the inlet E20 and the plate 2F, in the second zone Z2, through holes 23 produced in the plates 2G and 2H.

The circuit C2 has an outlet S20 formed by a hole 21 produced in the end plate 12. A second lower branch C22 or return branch of the circuit C2 extends between the outlet S20 and the plate 2F, in the second zone Z2, through holes 21 produced in the plates 2G and 2H.

The branches C21 and C22 are connected to one another by an intermediate branch C23 which is delimited between the plates 2F and 2G.

The circuit C′2 comprises an inlet E′20 formed by a hole 21 produced in the end plate 11. A first lower branch C′21 or forward branch of the circuit C′2 extends between the inlet E′20 and the plate 2C, in the first zone Z1, through holes 21 produced in the plates 2A and 2B.

The circuit C′2 comprises an outlet S′20 formed by a hole 23 produced in the end plate 11. A second upper branch C′22 or return branch of the circuit C′2 extends between the outlet S′20 and the plate 2C, in the first zone Z1, through holes 23 produced in the plates 2A and 2B.

The branches C′21 and C′22 are connected to one another by an intermediate branch C′23 which is delimited between the plates 2B and 2C.

In FIG. 10, the refrigerant fluid in the circuits C2 and C′2 circulates in a first direction, and the connection between the circuits C2 and C′2 is implemented by means of a connection conduit C3 which connects the outlet S20 of the circuit C2 to the inlet E′20 of the circuit C′2. Thus, the outlet S′20 of the exchanger 2100 as represented in FIG. 9 becomes the outlet S2 of the common circuit of heat-exchanging fluid formed by the combination of the circuits C2 and C′2. The inlet E20 becomes the inlet E2 of the common circuit C2 and C′2.

In the zones Z1 and Z2, the first circuit C1 has a single pass, from the edge M and towards the edge N. In other words, between the edges M and N and for the two zones Z1 and Z2, the fluid circulates in the first circuit C1 in a single direction, namely from top to bottom.

In the direction of circulation of the fluid of FIG. 10, the second circuit C2 and C′2 comprises a first pass or forward pass in the zone Z2, where the fluid circulates co-currently in the circuit C2, and a second pass or return pass in the zone Z1, where the fluid circulates counter-currently in the circuit C′2.

In FIG. 11, the direction of circulation of the fluid in the circuits C2 and C′2 is reversed. The inlet E2 is in the zone Z1 at the beginning of the circuit C′2, and the outlet S2 is in the zone Z2, at the outlet of the circuit C2.

In the direction of circulation of the fluid of FIG. 11, the second circuit C2 and C′2 comprises a first pass or forward pass in the zone Z1, where the fluid circulates co-currently in the circuit C′2, and a second pass or return pass in the zone Z2, where the fluid circulates counter-currently in the circuit C2.

Thus, regardless of the direction of circulation of the fluid in the circuit C2 and C′2, the exchanger 2100 comprises a pass that is co-current and a pass that is counter-current, which makes it possible to optimize the thermal exchanges.

Two exchangers similar to the exchanger 2100 and provided with the duct C3 can be used in a reversible refrigerating machine, in a manner similar to the exchanger 1100 as implemented in FIGS. 6 and 7. For the two directions of circulation of the fluid in the common circuit C, each exchanger comprises two passes, namely the outlet pass which is counter-current and the inlet pass which is co-current, which promotes thermal exchanges regardless of the direction of circulation.

The machine can be a water-water refrigerating machine in which the fluids that are cooled and heated by the exchangers 2100 are water.

It is also possible to use an air-water refrigerating machine including a first air-fluid exchanger also referred to as “battery,” and a second exchanger with two passes, such as the exchanger 2100.

FIGS. 12 and 13 represent a tube 500 incorporated in exchangers 3100 and 4100 represented in FIGS. 14 to 21.

The tube 500 is provided with a longitudinal slot 501 of width L. The slot 501 ensures the distribution of the fluid in the circuits C′2 of the zone Z2 of the exchangers 3100 and 4100 when they operate by evaporation. The slot 501 extends over most of the tube 500, the slot being interrupted at the ends so that the rigidity of the tube is ensured. In service, the slot 501 is oriented vertically towards the bottom of the tube.

The exchanger 3100 is overall similar to the exchanger 2100. It is provided with a connection conduit C3 which connects two circuits C2 and C′2 to one another. The circuit C2 comprises a single channel in the zone Z1, while the circuit C′2 comprises three channels in the zone Z2. The tube 501 distributes the fluid in the channels of the circuit C′2 of the second zone Z2 when the exchanger operates by evaporation.

The route of the refrigerant fluid in the circuits C2 and C′2, in reference to FIG. 14, is as follows for operation by evaporation: the fluid enters the channel of the circuit C2 through an inlet E2 located at the lower end N of the exchanger 3100. The fluid rises in this channel and joins the conduit C3 passing through an outlet S′2 of the circuit C2. The fluid circulates in the conduit C3 and enters the tube 501 through an inlet E′2 located at the upper end M of the exchanger 3100. The slot 51 distributes the fluid in the three channels of the circuit C′2. At the lower end N, on the opposite side from the tube 501, the three channels are connected to an outlet S2 of the exchanger 3100. The detail of the route of the fluid in the three channels of the circuit C′2 is indicated in FIG. 22.

The route of the refrigerant fluid in the circuits C2 and C′2, in reference to FIG. 15, is the following for the operation by condensation in the opposite direction from the operation by evaporation: the fluid enters the channels of the circuit C′2 through an inlet S2 located at the lower end N of the exchanger 3100. The fluid rises in these channels, enters the tube 500 through the slot 501 and joins the conduit C3, passing through an outlet E′2 of the circuit C′2. The fluid circulates in the conduit C3 and enters the circuit C2 through an inlet S′2. At the lower end N, the circuit C2 is connected to an outlet E2 of the exchanger 3100.

As for the thermal exchanges, the dual-pass exchanger 3100 achieves an optimal yield when there are two to four times more channels in the outlet pass of the circuit C′2 than in the inlet pass of the circuit C2.

FIG. 16 shows the exchanger 3100 with the inlet E2 and the outlet S2 of the circuit C2 at the top for operation by evaporation. FIG. 17 shows the exchanger 3100 with the inlet S2 and the outlet E2 of the circuit C2 at the top for operation by condensation. There are two to four times more channels in the outlet pass of the circuit C′2 than in the inlet pass of the circuit C2. FIGS. 18 and 19 show the exchanger 4100 respectively for the operations by evaporation and by condensation with the inlet and outlet of the circuits C2 and C′2 at the bottom. FIGS. 20 and 21 show the exchanger 4100 respectively for the operations by evaporation and by condensation with the inlet and the outlet of the circuits C2 and C′2 at the top. The exchanger differs from the exchanger 3100 in that it does not incorporate duct C3. The operation of the exchanger 4100 is similar to that of the exchanger 3100.

FIG. 22 shows the route of the fluid in a channel of the zone Z2 of the exchanger of FIG. 14 or of the exchanger of FIG. 18, operating by evaporation, with the slot 501 of tube 500 oriented vertically downward.

FIG. 23 shows the route of the fluid in a channel of the zone Z2 of the exchanger of FIG. 16 or of the exchanger of FIG. 20, operating by evaporation, with the slot 501 of the tube 500 oriented vertically downward.

In the context of the invention, the embodiments can be combined with one another, at least partially. 

1. Plate heat exchanger (1100; 2100; 3100; 4100) including superposed plates (2A-2L), which are inserted between two end plates (11, 12) and which channels for circulation of heat-exchanging fluid, characterized in that the channels delimit a first circuit (C1) for circulation of a first heat-exchanging fluid, comprising a single pass, and a second circuit (C2, C′2, C3) for circulation of a second heat-exchanging fluid, comprising two passes opposite from one another, so that, for each direction of circulation of the second heat-exchanging fluid in the second circuit, one of the two passes of the second circuit is co-current with respect to the pass of the first circuit (C1), while the other of the two passes of the second circuit is counter-current with respect to the pass of the first circuit (C1).
 2. Plate heat exchanger (1100) according to claim 1, characterized in that the first circuit (C1) comprises several intermediate branches (C13-C18) each delimited between two adjacent plates (2A-2L) and connecting to one another in parallel a forward branch (C11) and a return branch (C12) of the first circuit (C1).
 3. Plate heat exchanger (1100) according to claim 1, characterized in that the second circuit (C2) comprises two adjacent zones (Z1, Z2), in which intermediate branches (C23-C26) of the second circuit (C2) belong, for one of these zones, to one of the two passes of the second circuit, and for the other zone, to the other of the two passes of the second circuit.
 4. Plate heat exchanger (2100; 3100) according to claim 1, characterized in that the second circuit comprises a first portion (C2) and a second portion (C′2), which are separated by an intermediate plate (13) of the exchanger and which are connected to one another by a conduit (C3) outside of the exchanger.
 5. Plate heat exchanger (3100; 4100) according to claim 1, characterized in that the exchanger includes a tube (500) which is provided with a slot (501) distributing the second heat-exchanging fluid in several channels of the second circuit (C′2).
 6. Reversible refrigerating machine including a common circuit (C) of refrigerant fluid on which are arranged a compressor (400), a pressure reducing valve (200), and two exchangers (1100; 2100; 3100; 4100) which are each in accordance with claim
 1. 7. Refrigerating machine according to claim 6, characterized in that it comprises a four-way valve (V1) capable of changing the direction of circulation of the refrigerant fluid in the common circuit (C).
 8. Refrigerating machine according to claim 6, characterized in that the common circuit (C) is formed by the second circuit (C2, C′2, C3) of the exchangers (1100; 2100; 3100; 4100).
 9. Refrigerating machine according to claim 6, characterized in that the second circuit (C2, C′2, C3) comprises an inlet (E2) and an outlet (S2) arranged at the top the exchangers.
 10. Refrigerating machine according to claim 6, characterized in that the second circuit (C2, C′2, C3) comprises an inlet (E2) and an outlet (S2) arranged at the bottom of the exchangers. 